A New Circuit for Respiratory Signal Measurement Using Wearable Textile Sensors

• Main Authors: Chen, Chien-Nan, 陳建男
• Other Authors: Cheng, Mu-Huo
• Format: Others
• Language: zh-TW
• Online Access: http://ndltd.ncl.edu.tw/handle/04881214935709324399

碩士 === 國立交通大學 === 電機與控制工程系所 === 97 === This thesis presents a new circuit design for measuring the respiratory signal via wearable textile sensor electrodes. The basic idea is that the capacitance value between two sensor electrodes varies in corresponding with the respiratory signals because breathing causes the ups and downs of the thorax. Hence, a circuit which can measure capacitance variations can indirectly measure the respiratory signals. Conventional respiratory circuit design is based on the concept of AM (Amplitude Modulation) such that the amplitude varies in corresponding with the breathing. This thesis presents a new design which is based on the concept of FM (Frequency Modulation) such that the frequency varies in corresponding with the breathing. For realization, in this thesis, we use an IC 555’s oscillator circuit whose oscillation frequency varies with the capacitor between two sensor electrodes. Then a PLL (phase-locked loop) circuit is designed to estimate the frequency variations. The whole circuits are operated in a digital manner and hence it is simple for implementation. Note that the measured respiratory signals can be easily further used for measuring the respiratory rate.